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Chapter 10
Forests & Grasslands
Management
MANAGING AND SUSTAINING
FORESTS
• Instrumental Values of
Forests:
• Fuelwood: 50%
• Timber/lumber: 30%
• Pulp/paper: 20%
Figure 10-4
Types of Forests
• Old-growth forest: uncut or
regenerated forest that has
not been seriously disturbed
for several hundred years.
– 22% of world’s forests.
– Hosts many species with
specialized niches.
Figure 10-5
Types of Forests
• Second-growth forest: a stand of trees resulting
from natural secondary succession.
• Tree plantation: planted stands of a particular
tree species.
Figure 10-6
Rotation Cycles
• Short (fuel, paper) vs. long (hardwoods)
• Even-aged management – trees are same size,
age (tree farms)
• Uneven-aged management – different ages,
sizes – use selective cutting
Figure 10-7
Harvesting Trees
•
•
•
•
•
Building roads creates:
1) fragmentation,
2) habitat destruction
3) exotic species introduction
4) degradation.
Figure 10-8
Methods of Harvesting
Trees
• 1) Selective Cutting – take
intermediate to mature trees
– gaps are no larger than the
height of the trees
• 2) Clear cutting – take them
all
• 3) Strip cutting – cut strips
along the contour of the land
Figure 10-9
• 4) High grading – take out largest/best
specimens (also take out 16-17 other trees –
actually removes 50% - “cut the best, leave
the rest”)
• 5) Shelterwood – takes out mature trees in 23 cuttings over 10 years – prevents crowding
• 6) Seed-tree – leave only a few to reproduce
the forest
Harvesting Trees
Effects of clear-cutting in the
state of Washington, U.S.
Figures 10-10 and 10-11
Forest Pathogens
• Fungal – Chestnut blight, Dutch Elm disease
• Insects – Bark beetles (pines), Hemlock wooly
adelgid
Goals of Sustainable Forestry
– 1) Establish economic value of ecological services
– 2) Establish longer rotations in tree cutting
– 3) Protect old-growth and vulnerable areas
– 4) Certify sustainably grown trees
– 5) Minimize fragmentation of forests
– 6) Improve road building through forests
– 7) Leave snags for habitat
Figure 10-12
CASE STUDY:
FOREST RESOURCES AND
MANAGEMENT IN THE U.S.
• U.S. forests cover more area than in 1920.
• Since the 1960’s, an increasing area of old growth
and diverse second-growth forests have been
clear-cut.
– Often replaced with tree farms.
– Decreases biodiversity.
– Disrupts ecosystem processes.
Effects of Forest Fires & Types
– Advantages - Burn away flammable ground material
& release valuable mineral nutrients.
– Types: Surface – only burns undergrowth, leaf litter
– Crown – leaps from treetop to treetop
Figure 10-13
Controversy Over Fire Management
• Approaches to Fire Control:
– 1) Prescribed burns.
– 2) Allow fires to burn on public lands if they don’t
threaten life and property.
– 3) Clear small areas around property subject to fire.
– 4) Total supression.
Controversy Over Fire Management
• In 2003, U.S. Congress passed the Healthy Forest
Restoration Act:
– Allows timber companies to cut medium and large
trees in 71% of the national forests.
– In return, must clear away smaller, more fire-prone
trees and underbrush.
– Some forest scientists believe this could increase
severe fires by removing fire resistant trees and
leaving highly flammable slash.
Reducing Demand for Harvest Trees
• Use alternatives to
wood for
paper/pulp/
fuelwood
• (Kenaf (jute),
bamboo, hemp)
Figure 10-15
Forests in a Globalized Economy
• Timber from tree plantations in temperate and
tropical countries is decreasing the need for
timber production in the U.S.
• Hot Spots – areas with high biodiversity but have
imminent danger of losing it (25 worldwide)
• Conservation Easement – organizations
compensate poor areas for protecting selected
areas (debt-for-nature swaps)
• Buffer zone creation – large area around a core
of protected area
MANAGING AND SUSTAINING
GRASSLANDS
• ½ of world’s
livestock graze on
natural grasslands
(rangelands) &
managed grasslands
(pastures)
Figure 10-21
MANAGING AND SUSTAINING
GRASSLANDS
• Example of restored area along the San Pedro
River in Arizona after 10 years of banning
grazing and off-road vehicles.
Figure 10-22
Case Study: Grazing and Urban
Development in the American West
• Ranchers, ecologists, and environmentalists are
joining together to preserve the grasslands on
cattle ranches by:
– 1) Paying ranchers conservation easements
(barring future owners from development).
– 2) Pressuring government to zone the land to
prevent development of ecologically sensitive
areas.
Types of US Public Lands
• Multiple-use Lands: National Forests, National
Resource Lands – used for logging, mining,
grazing, farming, oil, recreation – provide a
“secure domestic supply of energy & strategic
minerals”
• Moderately-restricted use lands: National
Wildlife Refuges – can hunt, fish, mine, log,
military
• Restricted-use lands: National Parks, Wilderness
– only for camping, hiking, fishing, boating – no
roads, logging, vehicles, grazing unless it predates
designation
Stresses on U.S. National Parks
• 1) Overused
• 2) Inholdings (private
ownership) within
parks threaten natural
resources.
• 3) Air pollution
• 4) Exotic species
• 5) Too small to
maintain biodiversity
• 6) Poaching
Figure 10-23